Bicycles have been widely applied in many leisure and sporting activities and are one of many popular transport means for people in their daily lives. A bicycle rider applies forces on two pedals to drive a chainwheel or a sprocket to rotate, which in turn brings a rear wheel of the bicycle to rotate and provide a source of force for moving the bicycle forward. However, a bicycle rider, particularly an aged, a female or a child, might become exhaustive when riding uphill or riding for a long distance. To overcome this problem, an electric bicycle or a power-aided bicycle has been developed and introduced into market. With the electric bicycle, the rider may select to drive the chainwheel via an electrical driving assembly instead of the pedals.
While the electric bicycle is convenient, the structural design is complicated and it requires relatively high manufacturing cost. It is therefore a pity the electric bicycle is not widely accepted among consumers due to its high selling price. Moreover, the electrical driving assembly added to the bicycle is too heavy and occupies a considerable space, giving the bicycle an increased overall weight and somewhat cumbersome appearance. Another disadvantage in the currently available electric bicycle is that when the electrical driving assembly drives the chainwheel to rotate and thereby moves the bicycle forward, the rotating chainwheel would bring a pedal shaft assembly connected thereto to rotate along with it, causing two pedals connected to two ends of the pedal shaft assembly to rotate at the same time at high speed. Under this condition, the rider just could not position his or her feet on the pedals and would dangerously lose his or her balance on the bicycle to even cause an accident in a worse condition. Therefore, the inventor develops a clutch-type electrical driving device for the electric bicycle and a clutch-type drive thereof, in order to overcome the drawbacks existed in conventional electric bicycles and to increase the applicability thereof.